10 Historical Pigments—and Their Surprising Origins—from ‘The Universe in 100 Colors’

Magenta: You recognize it as the reddish-purple color of red onions, January’s birthstone, and the 2023 Pantone Color of the Year. Technically, however, magenta doesn’t exist. 

“Unlike other colors that correspond to a specific wavelength of light, magenta is something our brains create. When our eyes detect both red and blue light, our brains fill in the gap and invent magenta,” Terry Mudge, co-author of the new book The Universe in 100 Colors: Weird and Wondrous Colors from Science and Nature, tells Mental Floss. “It’s like a little plot twist in the story of color, reminding us that what we see isn’t just about the outside world; it’s also shaped by the way our brains interpret it.”

The Universe in 100 Colors is a lush journey through the countless hues that make up the world, from the relatively familiar—ivory, poppy red, chalkboard green—to the bizarre, like cosmic void, a black “that is the color of absolutely nothing,” or radium decay, the soft green glow of a chemical reaction. Natural and human-made colors are categorized as contextual (changing appearance depending on its environment) or fixed (remaining constant, like the yellow of a lemon rind), and even further classified according to their structure and wavelength. Large-format photos and intriguing biographies demonstrate the history and origins of each one.

Along with a hefty explanation of the science behind our perceptions of color, the book also presents an examination of how humans have used, interpreted, and appreciated it throughout time. “We use color to distinguish what foods are safe to eat and what animals are considered a threat. We use color to regulate our emotions and adorn our shelters; color can communicate and tell a story. So much of humanity is tied to color,” co-author Tyler Thrasher tells Mental Floss. “I find it fascinating that we’re so drawn toward this one (out of many) ways we can interpret the world around us.”

The book includes a selection of paints, dyes, and other kinds of pigments that come with fascinating—and even deadly—histories. Here are 10 of them, excerpted from The Universe in 100 Colors (out now from Sasquatch Books).

Carmine

There are some colors that we consume regularly, in both the capitalistic sense and the edible sense. Carmine red is one of these. This deep-­crimson extract has found its way into our foods, beverages, toys, packaging, and manufacturing. However, its first use as a dye dates back to 700 BCE.

While the word carmine can refer to a general family of deep, almost bloodlike, reds, it originated as an extraction from the scale insect Dactylopius coccus. The female insects are gathered and boiled in a sodium carbonate solution to remove any metals and contaminants, leaving behind carminic acid, which is separated from the solution to yield crimson lake. This fine red powder is the basis for dyes used in paints, pigments, and foods. It is then combined with a mordant similar to that of avocado tannin to ensure it binds to natural fibers and fabrics. 

To this day, carmine red is used in foods and even medicines. The dried remains of billions of scale insects pass through our bodies and lives on a daily basis—­if you read the ingredients for your favorite red candy or snack, you might find “cochineal extract” on the label. (Perhaps the idea of printing “dissolved insects” there seemed unappealing to the food and drug industry.) There are exciting developments afoot with the production of these red dyes, however, such as manipulating microorganisms into producing the pigment, which is more acceptable for use in vegan diets.

Egyptian Blue

Egyptian blue, a captivating pigment, has a rich story that begins with the distinction of being the first known synthetic color in human history, dating back to the 3rd millennium BCE. This vibrant azure adorned the monuments of the pharaohs as a symbol of the sky, water, and the river Nile. But beyond its historical significance, Egyptian blue possesses fascinating optical properties.

The pigment is produced by heating quartz, copper, alkali, and lime at temperatures up to 982°C (1800°F) for several hours before grinding the product into powder. As simple as it may sound, this knowledge was lost for nearly 1000 years, until scientists were able to reverse engineer known samples in the 1800s.

In normal light, it possess a soft matte blue appearance. However, under infrared light, Egyptian blue becomes intensely fluorescent, emitting infrared radiation more powerfully than any other known material. This unusual characteristic, unknown to ancient Egyptians, makes it detectable by modern infrared imagery and helpful in identifying archaeological sites that were once abundant in this pigment.

Modern science has been quick to recognize its unique value. Today the blue’s remarkable infrared properties are being explored for use in communication technologies, where it could serve to boost signal strength, facilitating faster and more efficient data transmission.

Egyptian blue’s journey from ancient civilizations to the cutting-­edge laboratory of today represents a fusion of past and future, a testament to the unanticipated path of scientific discovery.

Imperial Yellow

Humans have long used color to portray status, wealth, and power. For example, certain colors were reserved for specific individuals or positions within Chinese society, even going so far as to reserve one specific pigment only for the emperor.

Starting during the Zhou dynasty in China between 1046 and 256 BCE, a set of customs and rules regarding colors, patterns, and garments began to unfold. Certain colors and patterns were reserved for different seats in court or within royal families. And the rarer the color and more difficult to produce, the more likely it would be deemed suitable for the highest seat of power. 

Yellow is one of the colors in the five elements theory that defines traditional Chinese medicine; it represents the earth. Yellow became central within the theory when its association with the emperor was established. The earliest record of an emperor donning yellow was Emperor Wen of Sui prior to 600 CE. Between 649 and 683 CE, during the reign of Emperor Gaozong of the Tang dynasty, it was established that only the emperor and high members of the family and court could don any amount of yellow. The color also had a close association with the sun, and laws were soon established forbidding anyone else from wearing clothes pigmented with reddish yellow. This Confucian adage sums it up: “Just as there are not two suns in the sky, so there cannot be two emperors on earth.” These laws persisted until 1912 when the Qing dynasty fell after the Xinhai Revolution.

The royal appeal of yellow was also due to the time-­consuming and intensive process of creating this pigment, which required harvesting large amounts of Chinese foxglove tubers that were ground into a fine paste and applied to fabric. Approximately seven cups of dye were required to stain just 50 square feet of fabric, making this pigment rare and expensive.

Mauveine

Mauveine, or Perkin’s mauve, is born from the wondrous realm of accidents. Chemist William Henry Perkin stumbled upon this enticing pigment while trying to create a treatment for malaria. So many useful things have been discovered on the way to a loftier goal.

In 1856, at the age of 18, Perkin took on an assignment from his professor to attempt to synthesize quinine, the malaria drug of choice at the time. After repeated attempts, one of the failed samples left behind a black residue with bright purple remnants. Perkin immediately noted the unique potential of his accidental discovery and spearheaded its production. It quickly spread through the fashion and textile industry, with popularity soaring for nearly a decade before it was eventually replaced with similar synthetic dyes that came without the risk of working with aniline, a necessary component in synthesizing mauveine. (Exposure to the compound was observed to increase the risk of bladder cancer.)

Mauveine is known as one of the earliest lab-­made synthetic dyes in history and helped pave a path for the synthetic dye industry as a whole. The possibilities and potential of synthetic dyes outshined the capabilities of natural pigments and soon overtook the market. Only 12 years after the creation of mauveine, there were over 50 producers of synthetic dyes all racing to create and offer their colors as cheaply and widely as possible, forever changing how we interact with, create, and ultimately profit from color.

Mummy Brown

Humans have sunk to questionable depths to obtain the perfect colors. Whether it’s squashing thousands of insects and snails, poisoning themselves, or robbing graves, very little will get in the way of humankind’s pursuit of prized pigments.

Mummy brown was popular among painters for its varying degrees of ocher and umber. The yellowish-­brown hues were desired for depicting dark scenery and capturing nature, but this came at a cost: the looting and pillaging of burial sites—­usually burial sites of non-­white bodies. Egyptian tombs were often raided for the mummies needed to create this pigment, and when they were in short supply, the bodies of enslaved persons were unearthed and used instead. On certain occasions the bodies of mummified animals were also taken. Mummy brown was a fairly thin pigment, meaning it could be laid over other tones for shading or coloring purposes. It also contained fats, which meant the natural compounds of mummy brown would react with other colors, altering their appearance.

Eighteenth and 19th century artists Eugène Delacroix, Sir William Beechey, and Edward Burne-­Jones were known to use mummy brown, with Burne-­Jones reportedly burying his bottle in his garden after learning the truth of its contents. As the supply of looted bodies began to dwindle and the popularity of mummy brown waned, it was replaced with a more ethical alternative made of kaolin, quartz, goethite, and hematite.

Orpiment

Some colors are so tantalizing that they conjure fantasies of immense wealth, immortality, or exalted states of hypercreativity. Any ore, mineral, or pigment that comes close to resembling metallic gold has entranced kings, alchemists, and artists throughout history, even if it meant such pursuits resulted in a horrendous death by poisoning. Orpiment is a vibrant naturally occurring orange mineral rich in arsenic (and often found near volcanic activity, like realgar) that joins the exclusive club of colors that kill.

Everything about this mineral is dangerous, from the locations it was mined down to the very atoms that build its foundation. Like realgar, orpiment’s arsenic sulfide makeup was incredibly dangerous and toxic, especially since direct heating was required to bring out its fiery golden oranges. Before the revelations of modern chemistry, ancient alchemists would hover over furnaces heating orpiment to unlock the coveted orange color in the pursuit of gold synthesis, often poisoning themselves in the process. And while the alchemists were dying in their labs, works such as Raffaello Sanzio’s The Sistine Madonna and Giovanni Bellini’s The Feast of the Gods were harnessing the vibrancy of this pigment to captivate the world. The toxic nature of both the orpiment harvesting and production processes would eventually create a demand for replacement with cadmium-­ and chromium-­based yellows—­safeguarding a great number of creative lives.

Pompeiian Red 

In the mid-­18th century, as archaeologists gradually uncovered the ancient Roman city of Pompeii that was buried under ash and pumice in the eruption of Mount Vesuvius in 79 CE, they discovered a city brimming with opulence. Notably, the city boasted many frescoes featuring characteristic red backgrounds now known as pompeiian red. The local clay, rich in iron content, was thought to be the source of the vivid red pigment used throughout the city.

As the aesthetic significance of Pompeii was popularized, this color became associated with the sophistication and luxury of the city’s past. The discovery of pompeiian red ignited a design movement known as Pompeiian Revival. The trend, which coincided with a period of extensive archaeological work at Pompeii through the early twentieth century, had a particularly significant impact in the United States and Europe, where it influenced design of everything from furniture to architecture. The movement was distinguished by slender structural elements and large swaths of the signature red.

However, recent research introduces an intriguing twist in this color’s tale. Careful analysis suggests that the iconic red walls may have originally been a shade of yellow. The pigment yellow ocher is known for its ability to change to a reddish hue when subjected to intense heat, a transformation that could feasibly occur during a volcanic eruption. This would imply that the Vesuvius eruption not only destroyed the city of Pompeii, but may have also forged what we now consider the city’s iconic color.

Prussian Blue

​​While many colors find their niche in specific domains—­be it as a pigment, a medical treatment, or a chemical component—­Prussian blue stands out for its multifaceted historical impact across a range of disciplines.

Prussian blue was first created accidentally in 1706, when a paint manufacturer named Johann Jacob Diesbach was making red carmine pigment, and a contaminated ingredient in the recipe caused an unintended chemical reaction, producing iron ferrocyanide. To Diesbach, this chemical was uninteresting except for its distinct shade of blue, which he astutely marketed as an economical alternative to the expensive ultramarine.

Over a century later, the British engineer and inventor Joseph Whitworth used the same Prussian blue to create engineer’s blue, a type of grease which, when applied to metal where perfectly flat surfaces are required, can highlight tiny imperfections for correction. This invention dramatically aided in the development of high-­precision instrumentation.

Then, in 1842, chemist John Herschel discovered a photosensitive method for producing Prussian blue. This process was notably useful for the rapid duplication of documents, especially large technical drawings that we now call blueprints. A family friend, botanist Anna Atkins, used Herschel’s blueprint method to create images of her algae collection. She self-­published these works in the first-­ever book with photographs, titled Photographs of British Algae.

As if that wasn’t enough, Prussian blue is also an effective treatment for heavy metal poisoning caused by thallium and radiocaesium. This means pharmaceutical-­grade Prussian blue pigment is even available in pill form.

From revolutionizing the art world as an economical pigment to pioneering advancements in engineering and even serving as a lifesaving medical treatment, Prussian blue has proven its versatility time and again.

Scheele’s Green

Scheele’s green takes the cake as one of the more unfortunate pigments to grace this book. One of the deadliest greens ever invented, this bright and almost acrid-­looking color was invented in 1775 by German Swedish chemist Carl Wilhelm Scheele, who identified several elements and heavy metals throughout his life. The poisonous Scheele’s green was created by combining copper, oxygen, and arsenic, which yielded cupric arsenite. This novel hue found uses in paint for children’s toys, clothing dyes, wallpapers, and just about anything else that could be painted or dyed during the Victorian era.

Scheele’s green is notorious for its presence in a lethal wallpaper, as it is speculated that certain organisms could feed on the paper itself and cause arsenic-­related off-­gassing that would slowly poison the inhabitant. (Some fungi, such as Scopulariopsis, are capable of growing in damp conditions that contain arsenic.) It is believed that Scheele’s green wallpaper was responsible for Napoleon’s death because high levels of arsenic were found in his body.

History is lined with tales of laborers dying painful and unimaginable deaths from arsenic poisoning, ranging from the miners tasked with sourcing the cupric arsenite for the pigments to the children who worked in dimly lit workshops dusting fake foliage with Scheele’s green powder to make them appear more alive. The pigment’s tragic effects were eventually acknowledged, and public disapproval combined with government regulation and fading trends eventually laid this green to rest.

Tyrian Purple 

Extreme measures were often needed to bring purple into human hands, which is why historically its use was often reserved for royalty, the wealthy, or ceremonial purposes. Tyrian purple is no exception—­it was made at the expense of predatory sea snails.

Tyrian purple (also known as imperial purple or royal purple) was among the most expensive and intensive dyes to create. Tens of thousands of snails were required to produce just a couple grams of the raw dye, which was only enough to color a single trim for a garment, making it incredibly costly. It was said that a cloth stained with this pigment fetched its weight in silver. This color became such a powerful status symbol in Rome that just like imperial yellow, it too was eventually reserved for the emperor.

To make the dye, predatory sea snail mucus, the base ingredient, had to be procured. The snails secrete the mucus to sedate prey and coat their eggs—­or when prodded by humans. The two methods for extracting this mucus were either through “milking” (the more renewable option) or by crushing the snail itself. The freshness of the dye was critical to creating the deep purples and burgundies it was known for, meaning most of the extraction had to occur as close to the snail’s site as possible.

In November 2020, a team led by Byung-­Gee Kim at Seoul National University was able to synthesize 6,6’-­dibromoindigo, which is the molecule responsible for Tyrian purple. This was done by essentially tricking Escherichia coli bacteria into producing the molecule through engineering three separate enzymes into the bacteria and then centrifuging the 6,6’-­dibromoindigo into compacted pellets that can be applied to fabrics—­instead of annihilating thousands of snails.

Excerpted from The Universe in 100 Colors: Weird and Wondrous Colors from Science and Nature by Tyler Thrasher and Terry Mudge. September 24, 2024, Sasquatch Books. Published with permission.

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